Engine misfire leads to increased emissions and new regulations in California require misfire to be monitored. Engine misfire can be detected by monitoring the acceleration of the engine flywheel and checking that it is consistent with the firing of cylinders.
The applicant has recognised that where a vehicle is travelling over a rough road surface, the induced vibrations may have the same effect on the monitored acceleration of the flywheel as an engine misfire and thus the detection system may detect a misfire when none has in fact occurred.
The invention can also be used in other applications such as vehicle suspension systems where the vibration can be used as an indication of the evenness of a surface on which a vehicle is travelling